On the second occasion I got the infamous “Err 01”, I worked out that this was the common flex cable issue. I was able to salvage the use of the lens by using Aperture Priority with the aperture at the minimum.

As I was travelling at the time, I took the lens to the Canon store in Kashighar, China, they charged me 600 Yuan (roughly $100), only to have the issue reappear shortly after.

A second time I took the lens to a third-party repairer in Kathmandu, this time the lens worked for a few days and then the issue reappeared.